Terminal for inclosed fuse cut-outs



March 29, 1932.. H, J, HAMMER 1,851,249

TERMINAL FOR INCLOSED FUSE CUT-OUTS- Filed D80. 12, 1930 INVENTORPatented Mar. 29 1932 UNITED STATES PATENT OFFICE PZEBML'N J. HAMMERLY,OF WALLINGFORD, CONNECTICUT, ASSIGNOR TO THE TBUIMBULL ELECTRICMANUFACTURING COMPANY, OF PLAINVILLE. CONNECTI- CUT, A CORPORATION OFCONNECTICUT 'rnaiunmnron iwonosnn FUSE cur-ours Application filedDecember 12, 1930. Serial No. 501,779.

My invention relates to means for clamping the terminals of inclosedfuses in position in co-related fuse jaws.

It relates particularly to means for insuring a positive electricalconnection between the fixed and removable members for positivelymaintaining the fuses in operable position,

The form I have chosen to illustrate applies particularly to the type offuses which is provided with terminals of the knife blade type,-

although it is applicable to other types.

It has been the practice to provide a pair of spaced jaws to receiveeach terminal of fuses of this type, the jaws often being soldered inposition and mounted so as to project from a suitable foot block. Inthis usual type they have their projecting ends slightly bent orsprungtogether so as to provide a resilient engagement with the fuseterminals.

Fuse jaws of this type are usually made of copper or copper alloys,because of their high electrical conductivity, but the resilientproperty of these metals is limited and easily destroyed in case ofcontinued and/or excessive heat arising from poor electrical contactwhile in service, or other causes. It is possible to mount and assemblethe various parts of the fuses and the contact jaws at the factory sothat the contacting engagementwill be substantially perfect but, inshipping and subsequent handling, the jaws are uite likely to becomemore or less bent and t e' terminals of the fuses are V apt to be bentconsiderably out o alignment,

. so that by the time the fuse is put into service it is often the casethat the co-related parts will make a very poor electrical connection.Due to im erfect contacts it often arises that such conditions willresult in one or more 40 of the following undesirable conditions:

An undue resistance is set up in the circuit resulting in a drop involtage and a consequent loss of ower. v I The so may blow at a pointfar below its rated capacity, due to this waste dpower appearing asheatwhich may be,con ucted into the fusible element of the fuse and thuscause an unnecessary shut down of the power and heavy pecunia loss. I

Because of t e undue heating of the fuse particularly terminals the fusestrips may blow at the point where they are secured to the bladeterminals instead of at the center of the strip which is usually notchedto insure the blowing or fusing at a point or points substantiallymidway between the knife blade terminals where the strip is usuallysurrounded by granular insulating material and this condition oftencauses the burning of the fuse caps and terminals as well as thedetachable fastening means which are used in fuses of the renewabletype.

The are caused by an imperfect contact tends to pit or corrode andoxidize the parts, thus destroying their mechanicalfitting as well astheir electricalconductivity.

The undue heat tends to draw the temper and destroy the resiliency ofthe contact jaws which is usually relied upon to maintain a good contactand to hold the fuse in position.

Fuse jaws of some types are sweated or soldered into corresponding slotsin the supporting foot blocks and undue heating of the jaws tends tomelt the solder and results in a dangerous condition. 7

In fuse terminals of the type which includes copper jaws, the jaws arenecessarily comparatively thin in order to provide the requiredresiliency but these thin jaws are much more quickly heated and transmitthe heat to the fuse body much more readily than is desirable.

A principal object of my invention isto overcome or minimize thesedifficulties of the common-types of fuse terminals which have just beenpointed out.

Another object of this invention is to minimize the generation of heatat the point of contact between the fuse blades and the contact jaws orclips, and to provide good thermal conductivity and dissipative capacityfor radiating such heat as may be generated.

Another object is to prevent undue rise of temperature of the fusiblestrip of the fuse, by the conduction of heat thereinto because ofdefective contacts.

A further object is to prevent fuses from blowing out below their ratedcapacity, by

reason of surplus heat being conducted thereinto and exerting upon thefusible member of the fuse a melting action additive to the normalaction due to the passage of current therethrough.

Another object of my invention is to confine the fusion of theconducting member therein substantially to the portion thereof which isdesigned to dissipate the energy liberated upon rupture of the same byexcessive current.

Another object is to protect a fuse from having its fusible link meltadjacent to either of its end terminals.

A further object is to prevent pitting of contact by circuit rupturesoccurring at portions of the fuse closely adjacent thereunto.

A further object of my invention is to provide a form of fuse terminalin which the contact ends of the fuse may be securely clamped to insurepositive contact and to secure the fuse in position and yet may beeasily and quickly removed by means of a common screw-driver.

Another object is to provide a fuse clamping means including angularlydisposed'jaws from which the fuse is entirely freed for ready removalwhen the clamping member is released.

Another object is to provide a fuse terminal which is entirely free ofsoldered or pinned-together parts.

Another object is to provide an unusually rugged one-piece fuse terminalwhich may be depended upon for long service and to safely carry thecurrent up to the full rated capacity of the fuses.

Another object is to provide a fuse clamping means which is capable ofcorrectly ali ing the contact blades of a fuse with the use jaws eventhough these blades were not properly aligned at the factory or havebecome disarranged in handling.

Another object is to provide a fuse terminal having a one-piece jawmember so designed as to provide an unusual amount of metal and surfacefor absorbing and for radiating any heat caused by abnormal conditionsin the electrical circuit.

Another object is to provide a fuse clamping means including a roll orcam member which is loosely mounted at its center so that it is free toadjust or align itself with respect to the contact end of the fuse andto allow for a considerable wear of the cam itself or of the angularsurface of the co-related jaw member.

Fig. 1 is a front view of a cartridge type fuse mounted in supportsinvolving my invention.

Fig. 2 is a fragmentary sectional view on the plane of the line 22 ofFig. 1 and showing an end view of one of the supports.

Fig. 3 is a similar view of a modification.

A typical cartridge type fuse 5 has the usual terminal blades 6-6.

The support 7 is secured to the base or panel 8 by screws such as 9 and10 and the latter may also serve as an anchorage for the conductorterminal 11 The supporting member 7 has two flanges 12 and 13 which areintegral with the base of the su port and spaced sufliciently apart toreceive etween them the blade 6 of the fuse and a wedging member 14.

In the form shown in Figs. 1 and 2, the wedging member 14 is cylindricaland mounted on a screw threaded adjusting member 15 which is adjustablein the base of the support by mere rotation of the screw, so as to movethe wedging member in or out as the case may be. The inner walls of theflanges 12 and 13 in this form are tapered or inclined and convergetoward each other and toward the bottom of the space between them.

By properly proportioning the parts it will be seen that the blade 6 canbe forcibly pressed against the flange 13 by the simple expedient oftightening the screw 15 which draws the mem port.

In View of the fact that the two flanges 12 and 13 are substantiallyrigid it will be seen that there is practically no limit to the pressurewhich can be applied to produce contact between the blade 6 and theflange 13. The only part upon which there is any wear is the screw 15which can be readily replaced.

As the device is not dependent upon the resiliency of the usual springjaws or clips it will be obvious that heat will have but little if anyeffect upon the contacts.

It is also obvious that there is no danger of the fuse beingaccidentally disengaged. No amount of vibration will loosen the fusewhen it has once been properly inserted.

In the form shown in Fig. 3 the su port or holder has two flanges 12 and13'. e inner wall of the flange 12 is inclined and the other flange isat right angles to the base 7. In this case I have shown a wedge shapedmember 14' inserted between the inclined face of the flange 12 and thebase 6. This member 14 can be forced into place in any suitable mannerso as to produce an increased area of contact.

While it is desirable to employ a. wedging member which is of conductingmaterial it should be understood that some of the advantages of minvention might be attained with a non-con ucting wedge which can beforced or expanded into the space between the fuse blade and theopposite rigid wall or flange of the holder.

I claim:

1. A fuse holder including a metallic base having two flanges spacedapart from each other and projecting perpendicularly from the base, anadjustable wed ing member between said flanges, a screw aving a threadedengagement with the base and passing freely t er 14 into the narrowthroat of the suprough said wedging member and 2. A fuse holderincluding a metallic base.

member having two flanges projecting perpendicularly therefrom andspaced apart from each other to receive between them the terminal bladeof a fuse, at least one of said flanges having its inner face inclinedwith respect to the opposing face of the other L flange, a looselymounted wedging member movable toward and from the base, and meansaccessible from a point adjacent the outer ends of the flanges foroperating the wedging member to clamp the terminal blade of a fuse.

8. A fuse terminal clamp including a metal base having twoperpendicularly projecting spaced walls to receive between them a fuseblade, a self-aligning wedging means 1 located between said walls forclamping a fuse blade against one of said walls, said wedging meansincluding a member having convex side walls, said member being movabletoward and from the base and laterally with respect to said walls andadapted to tilt endwise, and means accessible adjacent the outer ends ofsaid walls for operating said wedging means.

4. A fuse terminal clamp including a metal base member havin two spacedflanges projecting therefrom an having oppositely disposed faces, theopposing face of one flange having a flat fuse terminal clamping surfaceand the opposing face of one of said flanges projecting angularly fromsaid base with respect to the opposing face of the other flange, aprojecting screw seated in said base with its head between the opposingfaces of said flanges, a substantially cylindrical clamping bar having arockable engagement with said screw and movable to clamp the terminal ofa fuse against the opposing'face of one of said flanges.

5. A fuse clamp including a metal base plate having two spaced flangesprojecting perpendicularly from said plate, each of said flanges havinga flat face opposed to the face of the other flange and' the face of oneof said flanges being inclined with respect to the face of the otherflange, a clamping screw having a threaded engagement in said base platebetween said flanges and projecting from said base plate, a clamping barpositioned between the opposed faces of said flanges and means ofconnection between said bar and said screw for causing the clamping orunclamping movement of said bar by the rotary movement of said screw.

6. A fuse terminal clamp including a metal base having two integralspaced flanges projecting perpendicularly therefrom, said flanges havingopposing faces, one of said faces having a flat surface and one of saidfaces being inclined with respect to the face of the other flange, aclamping screw seated in said base with its head between said flangesand projecting from said base, a clamping bar tiltably engaged by saidscrew and movable between said flanges by the turning movement of saidscrew to clamp the terminal of an inclosed fuse between said flanges.

7. A fuse terminal clamp including a metal base having two spacedflanges pro] ecting therefrom and having opposed faces, the opposed faceof one of said flanges being adapted for electrical engagement with aterminal of an inclosed fuse, the opposed face of the second flangebeing spaced apart from the said face of the first defined flange with asocket between the flanges to receive the terminal end of a fuse, andscrew means projecting substantially perpendicularly from said basebetween said flanges and laterally movable by engagement with one ofsaid flanges and having a laterally projecting portion to extend over apart of and force a terminal of an inclosed fuse into engagement ylviththe opposite face of said first defined ange.

8. A fuse terminal clamp including a metal base having two spacedflanges projecting substantially perpendicularly therefrom and with asocket between them for reception of the terminal end of a fuse, one ofsaid flanges having a face adapted to make electrical contact with theterminal of an inclosed fuse, the other flange having a face angularlyinclined with respect to the said face of the first defined flange andscrew means projecting perpendicularly from said base adjacent to saidinclined flange and positioned between the respective flanges, saidscrew means having an operating-end accessible at the front of thesocket and being movable laterally by engagement with said inclinedflange toclamp a terminal of an inclosed fuse against said face of thefirst defined flange.

HERMAN J. HAMMERLY.

